Two Breakthrough Technologies for Zero Water Leakage from Windows, Developed by YKK AP—Thoughts Behind the Development of the “W PROOF JOINT” and “Screw Hole Protrusion Processing”

There are three basic performance characteristics for windows: watertight performance, airtight performance, and resistance to wind pressure. If a window does not perform sufficiently in these areas, it cannot fulfill the natural roles required of a window, such as keeping water out of a house and maintaining a pleasant indoor environment. Among these characteristics, we focused on watertight performance for this article. We interviewed Yuya Oyama—who works in the Technical Research Division for the Materials and Manufacturing Process Technology Group, and is in charge of elemental technology development for materials—about two unique breakthrough technologies developed to guarantee quality.

Generally, the process of installing a window in a house involves the parts of the sash delivered from the manufacturing company (manufacturer), assembled as a window by an assembly company, and finally installed in a house aperture by an installation company. However, at that time, there was a question that could not be fully explained. No matter how many times we repeated internal verification tests, we were unable to replicate the leakages from the window frame. Upon investigating the situations at the window assembly site and during the window installation after assembly, it was surmised that the leakage was due to the creation of gaps at the window frame joints, caused by handling during transportation after assembly and variations in installation accuracy, and that the sealer was not properly performing its water blocking function. We had to develop water blocking technology which takes into account the variability of work during window transport and at the installation site. With this in mind, the development of a new sealer began.

While we began testing every conceivable idea each day to realize "leak-proof technology," we could not find a realistic means of achieving this goal. At that time, we noticed that there was a certain technology which had already been put to general practical use. That technology was a material called SAP (Super Absorbent Polymer), which is used in the field of civil engineering for waterproofing structures such as tunnels and bridges. Simply put, it is a highly water-absorbent resin material that swells when exposed to moisture. We thought that we could combine this material with a sealer to seal gaps tightly and prevent leakages when it rains.

If we could bring this idea to fruition, it would be possible to make a sealer which could stop water by swelling in response to rainwater, even if a window were to be installed with gaps in the window frame, while window assembly and installation by workers would remain unchanged. After focusing on this material, we considered how we could incorporate SAP material into our existing sealers. Through a series of prototypes, we sought to put it to practical use.

The two technologies introduced here are examples of how we have come to realize that technologies that we had been considering independently can be combined to great effect. We must continue to constantly incorporate new ideas and evolve our technology. As an engineer myself, I believe it is important to be interested in a variety of information, to find new ideas and hints for solving problems, and to create new technologies that will lead us in the right direction.

The housing industry is also faced with various issues these days, such as a shortage of sash and curtain wall installation technicians. While coming up with products that eliminate defects is one of our initiatives, we also need to think about ways to make installation easier. We intend to continue our pursuit of technology to create better products, such as making smoother installation a reality, through these efforts.